Engine that is equipped with continuous variable valve lift system

ABSTRACT

An engine having a continuously variable valve lift system, may include a camshaft having an input cam formed at one side thereof, wherein the camshaft is mounted on a cylinder head, a drum shaft that is disposed with a predetermined distance from the camshaft, wherein a swing arm is rotatably mounted at one side thereof, a control shaft that is disposed with a predetermined distance from the drum shaft, wherein a control cam that varies a position of the drum shaft is formed thereto, an output cam that is rotatably mounted on the camshaft and is connected to and moved by the swing arm, such that the output cam variably lifts a valve mounted in the cylinder head according to a position of the drum shaft,

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No. 10-2010-0042401 filed in the Korean Intellectual Property Office on May 6, 2010 , the entire contents of which is incorporated herein for all purposes by this reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an engine having a continuously variable valve lift system. More particularly, the present invention relates to an engine having a continuously variable valve lift system that continuously varies lift of a valve disposed at an intake port through which intake air is supplied to a combustion chamber.

2. Description of Related Art

In order to achieve optimal valve operation depending on the rotation speed of an engine, research has been undertaken on a variable valve lift (VVL) apparatus that enables different valve lifts depending on the engine speed.

The variable valve lift apparatus is necessary to securely fix a camshaft, a control shaft, and a drum shaft in a valve operating process using torque of the camshaft.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

BRIEF SUMMARY OF THE INVENTION

Various aspects of the present invention are directed to provide an engine having a continuously variable valve lift system having advantages of securely supporting a camshaft, a control shaft, and a drum shaft so as to variably control a valve.

In an aspect of the present invention, the engine having a continuously variable valve lift system, may include a camshaft having an input cam formed at one side thereof, wherein the camshaft may be mounted on a cylinder head, a drum shaft that may be disposed with a predetermined distance from the camshaft, wherein a swing arm may be rotatably mounted at one side thereof, a control shaft that may be disposed with a predetermined distance from the drum shaft, wherein a control cam that varies a position of the drum shaft may be formed thereto, an output cam that may be rotatably mounted on the camshaft and may be connected to and moved by the swing arm, such that the output cam variably lifts a valve mounted in the cylinder head according to a position of the drum shaft, a first cap, of which a lower portion thereof may be fixed on an upper portion of the cylinder head, and including a first semicircular portion sliding with an exterior circumference of the camshaft formed at one side of a lower part thereof, and a second semicircular portion sliding with an exterior circumference of the control shaft formed at the other side of an upper part thereof, and a second cap, of which a lower side thereof may be fixed to an upper side of the first cap, and including a third semicircular portion corresponding to the second semicircular portion formed at one side of a lower part thereof, wherein a guide slot through which the drum shaft penetrates may be formed at a center portion thereof.

The engine may further may include an input link connecting one end of the swing arm to the input cam eccentrically so as to rotate the swing arm on the drum shaft by the input cam, an output link connecting the other end of the swing arm to the output cam so as to rotate the output link on the camshaft, and a control link eccentrically connecting the control cam of the control shaft with the drum shaft so as to vary a position of the drum shaft disposed in the guide slot.

The engine may further include a guide drum that may be fixed on the drum shaft and moves along the guide slot.

A straight line connecting a rotation center of the drum shaft and a rotation center of the control shaft may have an ascent angle ranging from approximately 10 to approximately 30 degrees in a central direction of the cylinder head, wherein the camshaft may be disposed at a predetermined distance from the drum shaft in a lower direction of the drum shaft.

A first oil passage may be formed along a central line of the control shaft, a second oil passage may be diverged from the first oil passage and may be formed along the control cam, the control link, and the drum shaft, and a third oil passage may be formed along a central line of the drum shaft to lubricate sliding surface between the drum shaft and the swing arm.

As stated above, in an engine having a continuously variable valve lift system According to an exemplary embodiment of the present invention, a first cap may be fixed on a cylinder head, a second cap may be fixed on the first cap, a control shaft may be interposed between the first cap and the second cap, a camshaft may be interposed between the first cap and the cylinder head, and a drum shaft penetrates the second cap, such that each constitute elements may be securely fixed.

The methods and apparatuses of the present invention may have other features and advantages which will be apparent from or may be set forth in more detail in the accompanying drawings, which may be incorporated herein, and the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention.

FIG. 2 is a first partial cross-sectional view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention.

FIG. 3 is a second partial cross-sectional view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention.

FIG. 4 is a partial perspective view of a continuously variable valve lift system according to an exemplary embodiment of the present invention.

FIG. 5 is a partial exploded perspective view of a continuously variable valve lift system according to an exemplary embodiment of the present invention.

FIG. 6 is a partial exploded side-view of a continuously variable valve lift system according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings.

FIG. 1 is a partial perspective view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention.

Referring to FIG. 1, an engine having a continuously variable valve lift system includes a camshaft 105, an output cam 150, an input cam 130, an input link 135, a first cap 120, a guide drum 117, a worm wheel 114, a drum shaft 115, a control link 210, a second cap 125, a swing arm 140, a control cam 112, a control shaft 110, a cylinder head 100, and an output link 145.

The camshaft 105, the control shaft 110, and the drum shaft 115 are disposed to be parallel to each other with a predetermined distance therebetween, a tappet 310 is disposed at a lower portion of the camshaft corresponding to the output cam 150, and a valve 300 is disposed at a lower portion of the tappet 310.

The input cam 130 is formed at one side of the camshaft 105, and the input cam 130 has a circular section and is eccentric from a rotation center of the camshaft.

The swing arm 140 is disposed at one side of the drum shaft 115, and the input link 135 connects one end of the swing arm 140 with the input cam 130. In this case, if the camshaft 105 rotates, the input link 135 pulls or pushes out one end of the swing arm 140 by the input cam 130 such that the swing arm 140 rotates on the drum shaft 115.

The control cam 112 is formed at one side of the control shaft 110, and the control link 210 connects the control cam 112 and the drum shaft 115. In this case, if the control shaft 110 rotates, the control link 210 pulls or pushes the drum shaft 115 such that the position of the drum shaft 115 is changed.

The guide drum 117 is disposed at one side of the drum shaft 115, and the drum shaft 115 rotatably penetrates the guide drum 117. The guide drum 117 moves along a guide slot 127 of the second cap 125.

If the control link 210 pushes or pulls the drum shaft 115, the guide drum moves along the guide slot 127 of the second cap 125 to change the position of the drum shaft 115.

The worm wheel 114 is disposed at one end portion of the control shaft 110, a worm gear is engaged with the worm wheel 114, and the worm gear is rotated by a motor. A control portion controls the motor depending on the driving condition of the engine to rotate the control shaft.

The output cam 150 is disposed near the input cam 130 on the camshaft 105. Herein, the camshaft 105 rotatably penetrates the output cam 150.

The output link 145 connects one side of the output cam 150 with the other end of the swing arm 140 through a link member, and if the swing arm 140 rotates with a predetermined angle on the drum shaft 115, the output link 145 pushes or pulls one side of the output cam 150 such that the output cam 150 rotates on the camshaft 105 by a predetermined angle.

If the output cam 150 rotates on the camshaft 105, a profile portion that is protruded pushes the tappet 310 in a lower direction, and the valve 300 and the tappet are lifted a predetermined height.

The position of the drum shaft 115 is varied according to rotation of the control shaft 110 in an exemplary embodiment of the present invention, and the geometry through which the swing arm 140 moves the output cam 150 is changed such that the lift amount of the valve 300 is continuously varied.

FIG. 2 is a first partial cross-sectional view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention, and FIG. 3 is a second partial cross-sectional view of an engine having a continuously variable valve lift system according to an exemplary embodiment of the present invention.

Referring to FIG. 2 and FIG. 3, the camshaft 105 is disposed on the cylinder head 100, the first cap 120 is disposed to fix the camshaft 105, the control shaft 110 is disposed at a right upper portion of the first cap 120, and the drum shaft 115 is disposed at a left upper portion of the first cap 120. Referring to FIG. 1, the second cap is fixed on the first cap.

Referring to FIG. 2 and FIG. 3, a main gallery 200 is formed in the cylinder head 100 at a lower side of the control shaft 110 such that oil flows in a length direction of the control shaft 110. Herein, oil is supplied through the main gallery 200 with a predetermined pressure.

A first oil passage 230 is formed along a central line of the control shaft 110, a second oil passage 212 is diverged from the first oil passage 230 and is formed along the control cam 112, the control link 210 k, and the drum shaft 115, and a third oil passage 220 is formed along a central line of the drum shaft 115.

Referring to FIG. 2, a first ring 280 is formed at one end portion of the input link 135, and a second ring 282 is formed at the other end portion thereof. The input cam 130 is inserted through the first ring 280, and a pin formed at one end portion of the swing arm 140 is inserted through the second ring 282. Accordingly, if the camshaft 105 rotates, the input cam 130 pulls or pushes one end portion of the swing arm 140 through the input link 135.

A third ring 284 is formed at one end portion of the control link 210, and a fourth ring 286 is formed at the other end portion thereof. The control cam 112 is inserted through the third ring 284, and the drum shaft 115 is inserted through the fourth ring 286. Accordingly, if the control shaft 110 rotates, the control cam 112 pulls or pushes the drum shaft 115 through the control link 210.

Referring to FIG. 1 and FIG. 3, the drum shaft 115 penetrates the swing arm 140, and the swing arm 140 slides on an exterior circumference of the drum shaft 115 to rotate on the drum shaft.

In addition, oil supplied to the third oil passage 220 of the drum shaft 115 flows in an oil passage formed in the drum shaft 115 to effectively lubricate the sliding surface between the drum shaft 115 and the swing arm 140.

Referring to FIG. 1 and FIG. 2, structure and oil passages of a continuously variable valve lift system disposed at the right bank corresponding to the right camshaft 105 are explained, and since the structure of the left bank corresponding to the left camshaft is similar or identical to that of the right bank side, the detailed description thereof is omitted in an exemplary embodiment of the present invention.

Referring to FIG. 2, a straight line passing through a rotation center of the control shaft 110 and a rotation center of the drum shaft 115 is lowered in a central direction of a cylinder head. Further, the descent angle of the straight line can range from 10 to 30 degrees in another exemplary embodiment of the present invention.

FIG. 4 is a partial perspective view of a continuously variable valve lift system according to an exemplary embodiment of the present invention.

Rom Referring to FIG. 4, the first cap 120 is mounted on the cylinder head 100, and the second cap 125 is mounted on the first cap 120.

Further, a fixing bolt 520 sequentially penetrates the second cap 125 and the first cap 120 to be fixed to the cylinder head 100 such that the first cap 120 and the second cap 125 are secured to the cylinder head 100.

FIG. 5 is a partial exploded perspective view of a continuously variable valve lift system according to an exemplary embodiment of the present invention, and FIG. 6 is a partial exploded side-view of a continuously variable valve lift system according to an exemplary embodiment of the present invention.

Referring to FIG. 5 and FIG. 6, a first semi-circular groove 510 is formed outside the cylinder head 100 at a lower portion of the first cap 120, and a second semi-circular groove 500 is formed inside the cylinder head 100 at an upper portion of the first cap 120.

Further, a third semi-circular groove 505 is formed at a part corresponding to the second semi-circular groove 500 of the first cap 120 at a lower portion of the second cap 125.

Another semi-circular groove is formed at an upper portion of the cylinder head 100 corresponding to the first semi-circular groove 510, and the camshaft 105 is rotatably disposed through a circular penetration hole formed by the first semi-circular groove 510 and the other semi-circular groove formed at the upper portion of the cylinder head 100.

In addition, the control shaft 110 is rotatably disposed through a circular penetration hole formed by the second semi-circular groove 500 and the third semi-circular groove 505.

The third semi-circular groove 505 is formed at a lower portion of the second cap 125, and the guide slot 127 is formed at the center of the second cap 125.

As described above, the guide slot 127 is extended from the outside to the inside of the cylinder head 100 such that the drum 117 and the drum shaft 115 move inward or outward depending on the rotational position of the control shaft 110.

The fixing bolts 520 sequentially penetrate the second cap 125 and the first cap 120, are engaged with the cylinder head 100 to fix the first cap 120 and the second cap 125, and rotatably support the camshaft 105, the control shaft 110, and the drum shaft 115.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. 

1. An engine having a continuously variable valve lift system, comprising: a camshaft having an input cam formed at one side thereof, wherein the camshaft is mounted on a cylinder head; a drum shaft that is disposed with a predetermined distance from the camshaft, wherein a swing arm is rotatably mounted at one side thereof; a control shaft that is disposed with a predetermined distance from the drum shaft, wherein a control cam that varies a position of the drum shaft is formed thereto; an output cam that is rotatably mounted on the camshaft and is connected to and moved by the swing arm, such that the output cam variably lifts a valve mounted in the cylinder head according to a position of the drum shaft; a first cap, of which a lower portion thereof is fixed on an upper portion of the cylinder head, and including a first semicircular portion sliding with an exterior circumference of the camshaft formed at one side of a lower part thereof, and a second semicircular portion sliding with an exterior circumference of the control shaft formed at the other side of an upper part thereof; and a second cap, of which a lower side thereof is fixed to an upper side of the first cap, and including a third semicircular portion corresponding to the second semicircular portion formed at one side of a lower part thereof, wherein a guide slot through which the drum shaft penetrates is formed at a center portion thereof.
 2. The engine of claim 1, further comprising: an input link connecting one end of the swing arm to the input cam eccentrically so as to rotate the swing arm on the drum shaft by the input cam; an output link connecting the other end of the swing arm to the output cam so as to rotate the output link on the camshaft; and a control link eccentrically connecting the control cam of the control shaft with the drum shaft so as to vary a position of the drum shaft disposed in the guide slot.
 3. The engine of claim 2, further comprising a guide drum that is fixed on the drum shaft and moves along the guide slot.
 4. The engine of claim 2, wherein a straight line connecting a rotation center of the drum shaft and a rotation center of the control shaft has an ascent angle ranging from approximately 10 to approximately 30 degrees in a central direction of the cylinder head.
 5. The engine of claim 4, wherein the camshaft is disposed at a predetermined distance from the drum shaft in a lower direction of the drum shaft.
 6. The engine of claim 2, wherein a first oil passage is formed along a central line of the control shaft, a second oil passage is diverged from the first oil passage and is formed along the control cam, the control link, and the drum shaft, and a third oil passage is formed along a central line of the drum shaft to lubricate sliding surface between the drum shaft and the swing arm. 